Fluid packed drill collar



F1. D. DE JARNETT yFLUID PACKED DRILL COLLAR Nov. 26, 1957 3sheets-sheet 1 Filed 'May 26, 1954 m), MM M IN V EN TOR.

F. D. DE JAR'NETT FLUID PACKED DRILL COLLARA Nov. 26, 1957 5Sheets-Sheet 2 Filed May 26, 1954 IN V EN TOR.

Nov. 26, 1957 F. D. DE JARNETT 2,814,452

' FLUID PACKED DRILL COLLAR Filed May 26, 19.54 3 Sheets-Sheet 5 l. L Amm1- ,Illy

fn/VK f bl/WYE?? INVENTOR.

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United States Patent() Vthe rotary drilling bit lat the bottom of `thecolumn commonly create suchstrainvand-fatigue the `metal of the drillingcolumn as tocause structural failureorftwistoffs. The :failures occurlatscrew threads whichrare .the `weakest vpoints in the drilling column.More `often ythan `not the failures occur in the lowerparttofthe .drillcolumn but they mayoccur in drill vcollar threadsfortool joint threadsat any rlevel.

rThe factors that determine the'ffrequencyand amplitude ofthe vibrationand of the shock forces -include therate of rotation of thedrilling'bit, the pressure applied 'to the drilling bit, the kind ofLformation encountered 'by the drilling bit, the slope offthelformation,etc. Usually `the forces involvedtend to -be excessive .as `thedrillingbit makes the transition from one formation to another. Y

The rate of vrotation of the -drillingbitfmay vany lfrom 40 R. l. M. to500 RF. M. or higher and, of course, vibration increases with the4.speed of rotation. -fUsually a relatively high rate ofvrotationiisfdesirab'le but yis not .permissible because .of thedestructive effect of the re sultant vibration.

The pressure imposed on the rotary bit varies from 300 to 2500lbsperfinch diameterof the hit.` YThusgthe total pressure varies fromy1/2 ton .to l2`5 ftons. More than tons is .seldom'necessarv If thedrilling bit pressure were obtained by placing most or all of the drillcolumn .under longitudinal compression, the Yresult would :be :the.creation .of excessive and destructive stressesatethe .drill collarsandtool'joints in the drilling column. AAnd .afurtherresult would be thelikelihood =of diverting `the .drilling from .the .desired For thesereasons 'the\desired;pressure at the rotary bit is providedby-adding-weightftothe.lowerend of the drilling column. The`added weightis obtained by a drill collar assembly consistingtofwa .seriesofindividual drill .collars substituted .for lengths `ofdrillpipe at `theylower end ofthe drilling column. Such .individual drill collars lareusually made'.by..machining.and boring solid lengths of steel `toYprovide.heav,y `tubes `with relatively ythick walls. Themachining, and.especiallythe boring, is expensive sothat'such individualdrillcollarsare relatively costly items.

YTo avoid subjecting the drill pipe of V'the .column .to such excessivecompressive stress with vresulting .fatigue and failure, the weight.onthe .rotary 'bit should never exceed that of the drill collarassembly and preferably should normally be not more "than'half'thevveightdfA the drill collar assembly. Thus allcompression'in'the drillcolumn is lconfined "to the 'drill collar 'assembly 's'o :that the majorportion of the 'drillco'lumn is under -tens'ion rather than compressionin "the drillingffofa deep fwell.

It is apparent that the drill collar assembly will=usually haveconsiderable weight.l A drillfeollar assembly as ylong as 180 feet andweighingias'QrinlchA astS tonslisfnot unusual.

In some 'types tof formations, rsuehffas v:brittle rshales,

4gumbos J and conchoi'dalffracturing flimestones, f there is 11a deniteupper -limit-ato A:the 'rbitg pressure that can .be used efliciently,higher bit pressures reducing the rate of ICC 2 penetration. More rOftenthan not, however, there is reason to use Ya relatively high bitpressure along lwith a `relatively vhigh rspeed of rotation. 'Thus insome formations, such as limestone developing angular fractures, salt,very hard sandstones `or quartzites, and igneous rocks, "the rate ofpenetration ofthe bit appears 'to increase as a straight line function'with increase Ain bit pressure, irrespective Vof the rotating -speedand volume of fluid cirlculated. Again in other y'formations such assoft sandstones, sandy shales and silts, vthe rate lof penetrationrincreases directly with weight on the bit if uid circulation androtational speeds are proportionately adjusted.

lSome of the ycauses #of vibration and shock may be readily understoodbymconsidering -the manner in which a drilling bit functions. At theproper bit pressure the Jdrilling bit fembeds itself in the formationjust enough to --permit it to chip away the `rock yin small fragments=as fthe stem revolves. inevitably, however, situations arise andpersist lfor periods of .time in which the bit pressure is excessive forthe particular formation. In 1that event, Ythe bit'will embed itself inthe rock to such extent that it `cannot `cut itself free. lSince thedrilling bi't cannot -cut zitself vfree it repeatedly jumps loose toycause a chattering action that strains the whole equipment. Thetremendous weight .of -the usual drill collar fassem'bly 'is added tothis chattering action. It is this kind of vstrain that commonly `causestwistoffs with the lpenalty of added 'labor `and lloss of drilling time.To :avoid :such consequences :drillers are vcommonly forced -to :bevvery :conservative -in drilling -speeds and pressures.

The 'presentinvention alleviates Vthe eifects of vibration, '-.c'hatter,and :other forces generated at the drill bit, by .providing .fa drillcollar'constructionwhich will 'cause such forces to "beatleast partiallydampened anddissipated at tthelower end of thedrilling column. It iscontemplated .that'each individuahdrill 'collar in the series of drillcollars will labsorb a tportion of the forces transmitted thereto frombelow so :that the Aseries=ofldrill collars in the drill "collarassembly vwill have :a desirable cumulative effect on `the engenderedforces.

In .general Jthe fdesired'eifect is attained by mounting :massesofm'aterialfon the lower `end of the drill columnwithfreedomforlmovementof themasses relative to the drill fcolumn.Energy-isdiverted from the solid structure` fof the drill column bytransmission'lto these masses of material to cause independent-movementthereof. Energy fis'dissipated, in part, byfriction involved in 'therelative Vm'ovements of the added masses. Energy' dissipation alsoA.arises yfrom the 'fact that the -masses being largely free from.controlmove yat random relative yto the solid structure of the drillcolumn, so that a vibratory or shock Vmovement of thexdrillcolumnstructure-in one longitudinal =directi`on lmay .result in .an impactagainst a free mass Ymoving-.inthe opposite direction, energy beingabsorbed advantages @peculiar Ito .each.of.the .twot kinds of material,

but also provides a certain dashpotaction in the inter- .ference .by.the .liquid with* the .movements of .the solid material.

The solid material in the various practices of"thein vention maycomprise a small number of relatively large solid bodies or a largenumber of relatively small solid bodies and may even comprise finelydivided solid material. An important advantage of combining liquidmaterial with solid material is that it makes it possible to cause theSolid material to seek any desired normal position within its range ofvertical movement.

lf a liquid is selected that is of lower specific gravity than the solidmaterial immersed therein, the solid material will seek a normalposition at the lower limit of its range of relative vertical movement.ln such an arrangement the solid material responds primarily to upwardcomponents of movement of the drill column and has maximum freedom forupward movement in response to such upward components. lf the liquid isselected for a higher specific gravity than `the so-lid material tocause the solid material to lloat thereon, the solid material may becaused to seek a normal position at the upper limit of its range ofrelative vertical movement. Thus the solid material will respondprimarily to downward components of movement ot the drill column andwill have maximum freedom for movement in response to such downwardcomponent.

it the liquid has a higher specific gravity than the solid material, thevolume of the liquid relative to the volume of the coniined space andthe volume `of the solid material may be selected to cause the solidmaterial to tend to oat at any desired intermediate level in its rangeof relative movement. The solid material will then have freedom forvertical movement in both directions from its normal position and willnot make direct impact with the solid structure of the drill columnunless it reaches one or the other of the two limits of its range ofvertical movement.

lt is apparent that a drill collar assembly made up of a series ofindividual drill collars may comprise a variety of individual drillcollars for a variety of individual eteets. Thus in some drill collarsof the assembly masses of solid material will normally seek the lowerlimits of their ranges of movement; in other drill collars of theassembly, the masses of solid material will normally seek the upperlimits ot' their ranges of movement. In any event, a drill collarassembly incorporating relatively movable masses of material in accordwith the teachings of the invention will absorb, dissipate and dampenvibratory forces and shock forces to minimize the structural failuresthat are commonly caused by vibration and shock. Such a drill collarassembly will permit a higher than usual rate of rotation of thedrilling bit with consequent higher than usual rate of penetration bythe bit.

The various features and advantages of the invention may be readilyunderstood from the following detailed description considered with theaccompanying drawings.

in the drawings, which are to be regarded as merely illustrative:

Fig. l is a simplified diagrammatic view of a drill column in a borehole with the lower end of the drill column provided with a drill collarassembly as taught by p the present invention;

Fig. 2 is an axial section of a portion of the drill collar assembly inFig. 1 showing the construction of an individnal drill collar in theassembly;

Fig. 3 the line 3-3 of Fig. 2;

Fig. is a view, partly in side elevation and partly in section, showinga `second form of individual drill collar that may be used in the drillcollar assembly;

Fig. 5 is a transverse section taken as indicated by the line S- of Fig.4;

Fig. 6 is a view similar to Fig. 4 showing athird form of individualdrill collar that may be used;

Fig. 7 is a similar view showing a fourth form of drill that may beused;

is a transverse section taken as indicated byK Fig. 9 is a similar viewof a still further form of drill collar construction that may be used;and

Fig. l0 is a transverse section taken as indicated by the line 10-10 ofFig. 9.

Fig. 1 shows schematically an oil well bore 20 in which a drillingstring or drill column 2 carrying a drilling bit 22 is rotated in theusual manner by the rotary table 23 of a drilling unit at the top of thewell. The lower portion of the drill column 21 comprises a drill collarassembly, generally designated by numeral 24, which, in turn, comprisesa series of individual drill collars 25. Any number of individual drillcollars 25 may make up the drill collar assembly 24, the number beingdetermined by the weight that is desired on the drilling bit 22.

Fig. 2 shows one embodiment of an individual drill corlar, generallydesignated 25a, which may be incorporated in the drill collar assembly24 of Fig. l. The construction shown in Fig. 2 includes an inner steeltube 3d and a shorter outer steel tube 31 which together form an annularspace or chamber 32. As best shown in Fig. 3 a series of I-beams 33 maybe positioned longitudinally in the annular space 32 to serve as spacersand to provide reinforcement for the two tubes. The I-beams 33 may beattached to the inner steel tube 30 by welding.

The upper end of the inner steel tube 3i) is threaded into a tool jointbox 35 in a fluid tight manner. The iluid tight fit may be accomplishedby threading the inner steel tube 30 in to the tool joint box 35 whilethe tool joint box is heated so that the tool joint box will shrink intoa pressure t with the inner steel tube. United with the tool box joint35 by welding 36 is a sleeve extension 37 which embraces the inner steeltube 30 and is attached by welding 40 to the upper end of the outersteel tube 31 to close the upper end of the annular compartment 32. Inthe construction shown, the sleeve extension 37 has an end portion 41 ofreduced diameter to t into the end of the outer steel tube 31. The endof the outer steel tube 31 is bevelled as shown to permit the welding 40to lie inside the desired maximum diameter.

In like manner the lower end of the inner steel tube 3i) is threadedinto a tool joint pin 44 in a iiuid tight manner. Connected with thetool joint pin 44 by welding 45 is a sleeve extension 46. The sleeveextension i6 has a reduced end portion 47 that tits into the lower endof the outer steel tube 31 and is attached thereto in a uid tight mannerby Welding 48 to form the lower end of the annular chamber 32.

It is contemplated that the annular chamber 32 will be partially lledwith a suitable liquid in addition to containing the I-beams 33. Anysuitable arrangement may be provided to make it possible to introduceliquid into the annular chamber and to drain the liquid out of thechamber when desired. For this purpose each of the two sleeve extensions37 and 46 may have a short longitudinal bore 50 communicating with aradial bore 51 to provide a passage for communication between theannular chamber 32 and the exterior. The two radial bores 51 may beclosed with suitable screw plugs 52 to connc a body of liquid in theannular chamber 32, Pref erably the liquid level is slightly below theupper end of. the annular chamber 32, for example, as indicated at 55,to provide room for thermal expansion of the liquid.

Any suitable liquid may be used, including relatively heavy liquids aswell as relatively light liquids. For example, the liquid may bemercury, oil or water. ln some instances it will be desirable to use arelatively light fluid having a low freezing point, for example,glycerine or alcohol.

If the annular chamber 32 contains mercury the total weight of theindividual drill collar 25a including the mercury will be of the sameorder of magnitude as the Weight of a conventional solid steel drillcollar but the freedom for movement on the part of the confined mercurybody will provide a desirable damping effect on faisaarea the mercury.l`Downwarn movements :of [the erin cenar engendered fb'y the 'drill bit,however, fare fnotopposed by the ittljhe'rti'a lof the mercury fbdybecause libere :is fredonljfdr relative vertical movement 'between iure'meriiiiy lbod-y an'd 'fth'e confining structure fof 'the Sdr'illcollar.

In afdoivnwardmovemeiit of lthe drill column "thec'o'n- #lined'r'ne'rcry body ten'ds lto romain fstationary but 'this ftnd'ency isopposed fby Jthefr-iction between the mercury fanti the *verticalinetalsurfac'e's including :the imany vertical fsufaces -of thevlI-ibeams :33. :In addition `the tende'r'ioyfo'rthefmrcy Abodytorernain stationary when the 'drill column "1i-loves verticallyvdownward l-is opposed by the-air body linithe ich'ainbe'r 32 above the=liquid level of fthe mercury "It `lis apparent fthat 'when :thevlmercury colilnih Iin lthe"cliainber 32is ylifted bodily by an upward`tli`ru`s of'tlie drill-column andtlielupwardf-thrust is-abrupt- '1l-yterminated, 'the 'mercury will tend to continue its `up--w'a'cllmove'ment 'and will 'be fdeceler'ated by-frictio'naltrefs'istan'ceandf-by'displacementfof the 'air body andimpact `o'f the 1'nrc1'1`ry fagainst the upper end lsurfaces of `thefenaniberlsz. g

"lliref'inof course, -a slight delay'involved'with respect to -th'eiiinpact of ftherne'rcury 'bodyagainst the upper 'endlwallffthechaniber. 72VIf theldrill column is vibrating, the'fviliratbryu'pward thrust AWof the drill column 'will 'be followedlimmediately by a downwardth'rusta'nd'thefimpact of the r'nercury against`the upper =end wall of the cli'amb'erinayoccur at 'a time'to oppose'thedownwar'dfmove- 'ine of `the "drill column. Thus, more -often tha`nfnot, T`th`e mercury lwill oscillate' out` of phase 'with respect to the'v'erticalfvibrator'y movementof thefdrill coluninj the outzof lphaser"relationship providing -a desirable 1 damping action.

Theindividual drilll'collar 25h shown iin Figs. 41' and y5isfl'argely'id'entical with the f lirstdescribed embodiment/asindicatd'by the use of corresponding nme'ralsuto indicate'correspontlingl'parts. VIn this second-embodiment'iof the invention theflibe'ams vare'omitted andthe annular cham- IAbei' TST-ofthedrillfcollar structure 4is occupied bya single "solid lmetal bodytogether Ywith a body vof mercury in which thesolidbodyisfatileastpartiallysubmerged. The Isolidlr'netal'bodyiisfinvthe'fo'rm of heavy `tubular membe1"60,whichmay'be a heavysteeltu-bedimensioned yfor :free longitudinal \moverne`rit `in 'the annularchamber 32. The 'heavy Psteel ytubular `body'60 'is immersed in 'ia=body 61 lof mercury and tendsito float Ton the mercury body.

vinercuryfmay Yextendtoa liquidil level 62, A1for ex- F-anple," whichfisat'a sulficientfe'levationto zh'old thetbular body 60 against the upperend of the-chamber-32 '.understatic conditions. It `will benotedthat-therens a `^substantial;airspace above tlie vliquid leve1 62vlwhich=not only allows for thermal expansion of-the-tubula'r bodyandof'themerc'ury bodyi' 61, but also=provides space 4for f'surgin'g4#action of 'the mercury.

fi'Si'nce' the `metal tubular body 60v is normally in'- contact with theupper'end f theannularechamberzlitiis apiparentthttlie tubular body 60`will respond directlyand ib'odily todownward thrustsoffthe'drill-column;and?itis further apparent that there is room for asubstantialrange tofrelative'downward movement of thetubular--body 60from its `normal `static vposition relative to the structure of thedrill column. y

Downward movement of the tubular metal body 60 relative tothe-drillcolumnvis opposed,vrst, by the tendency of the tubular body to floatand, second, by the resistance of ythe mercury toupward Ydisplacementthrough tlie narrow longitudinal spacesinsidecand Outside "o'f the"itubulr bo'dy 60. There is a certain'dashpot/actionlin- 'volvedlin' therestriction of-the upward "ow o`f"the"m`er -cury.

-It is lapparent that an abruptly 'terminated' downward'thrust-on'the-part-of the drill column will result inVcontinuedvdownward "movement of the solid -tubular 'bodyf60 zinfannular chamberwith consequentdisplacement'otfmercury and `that the solid tubular bodywill 4then seek fto return lto its normal upper floating position. The#solid tubular `body returns toits normal upper position afte'r anappreciable time delay and `in 'nany Vinstances lthe solid tubular bodywill make thisfupward returnimovement-in synchronism with a downwardtlir'ustiof the drill column to oppose the ldownward thrust. Thus, =hereagain, the freedom for a relatively :movable mass of material toreciprocate out of phase lwith lthe longitudinal reciprocation ofthedrill column is importantin modifyying the action of the drill columnby dampingleffectsand energy dissipation.

The third form of fthe linvention comprising -thein'dividual drillcollar 25c'shown'in Fig. f6 `is `identical with ythe form shown in Fig.4 as indicatedby the'u'se of-identical numerals to designate identicalparts. -In .this -instance, however, the bodyof mercuryis'replaced-by-abody 66 of relatively light lliquid, for example, Water, which liquidhas a normal static ylevel 67. Since .the liquid is-of muchlessfspeciiic gravity than-the solidtubular body60, thetubular'bodynormally seeks a position Aat the Vbottom of the annularchamber 32 as 'lshown'in Fig. 6.v There is freedom for relativemovementlof the body of liquid 66 because the normal liquid level 67-isvspacedsubstantially below the upper end of the annular chamber.

In the embodiment of the invention; shown in Fig. V6, the solid tubularbody 60 responds directly Dto 'upward thrusts of the drill column andhas a rangefor-relative upward 'movement in response to such thrusts.vThe `upward movement of the solid tubular body -60 is opposed bygravityand by frictional resistance. lIt is also Atube `noted that any upwardmovement of the solid tubularbody 60 that contracts the space aboveythenormal'level 67 will be opposed by the compression of air -bodytherein. f 4desired this air may be normally under ypressuresubstantially-above atmospheric.

If lthe relative upward movement of the solid tubular -body 60 in the-annular -chamber -32 results in downward displacement of the liquidinto ythe lower end of the chamber, there will be a certain dashpotaction to resist both the relative upward `movement and the returndownward movement of the solid tubular body since -the liquid is forcedthrough restricted longitudinal spaces inside and outside lof thesolidtubular-body. Here again it is apparent'that the freedom for the4'solid tubular body 60 to reciprocate vertically out of. phase with thevertical reciprocations of the drill columnis important.

Fig. 7 shows another embodiment of the'inventioncomprising an individualdrill collar V25d which :is identical with the previously describedindividual drill collar'ZSb of Fig. 4 except for the quantity of mercuryemployed. In Fig. 7 the body of mercury A'l0 is of'less quantity thanthe body of mercury 61 invFig. 4, being'at-alowernormal liquid level 71so that the solid tubular lbody A60m Fig. 7 v has a normal oatingposition intermediate the two ends of the annular chamber 32. Thus atthe normal position of the solid tubular body 60 in Fig. 7 the solidtubular body has freedom for verticallongitudinal movement in bothdirections. Itis apparent that vertical movements of the drill column ofrelatively low ymagnitude will merely cause the float 60 in Fig. 7 tobob up and down without the iloat reaching either end of `theaunularspace.y This bobbing action will beresisted by inertia, friction and bya dashpot action, all of which vtend to modify vibratory and shockforces in a desirable lmannen Vertical movements of the drill column ofrel-ative large amplitude will cau-se thesolidtubular body y60 of Fig. 7to reach one'or bothends ofthe annular chamber 32'to make impact againstthe solid structure of the vdrill column. n

The individual drill collar 25e shownV in Fig. 8- isof the sameconstruction as heretofore described exceptfor the ""contentsofftheannular cha-mber-32. flnthsinstance, the

annular chamber 32 contains a mass 72 of solid material in the form ofrelatively small bodies. The mass 72 may comprise, for example,relatively small steel balls. This mass 72 of bodies of solid materialis immersed in a liquid body 73 of relatively low speciiic gravity, forexample, water, the liquid body having a normal level 74 spacedsubstantially below the upper end of the chamber.

This embodiment of the invention shown inFig. 8 operates in much thesame manner as the embodiment shown in Fig. 6, since in both instances amass of solid material is normally at the bottom of an annular chambercontaining a liquid. It is to be noted, however, that when such a massof small bodies is thrown upward from the bottom of the annular chamber,the individual bodies of the mass tend to `separate so that the returnimpact of the mass against the bottom of the annular chamber isattenuated less severe than the sharp return impact of a solid body.Another difference is that the mass of small bodies forms numeroustortuous passages for relatively great resistance to displacement tlowof the liquid when the mass shifts vertically in the annular chamber.

The liquid body 73 may be omitted in the form of the invention shown inFig. 8 if desired. It the liquid is omitted the individual bodies makingup the mass of solid material will still tend to separate when the massis lifted from the bottom of the annular chamber. Here again, the returndownward movement of the solid material will result in less severeimpact against the lower end of the annular chamber than would occur ifthe solid material were all in` one piece.

The individual drill collar ZS of Fig. 9 is similar to the individualdrill collar of Fig. 8 but in this instance a mass 80 of small solidbodies for example, steel balls, floats on a body of mercury having anormal liquid level 81. In this instance, the liquid level is highenough to force the mass 80 against the upper end o the annular chamber32. Thus the arrangement shown in Fig. 9 is the reverse of thearrangement shown in Fig. 8 in that the mass of small bodies respondsprimarily to downward thrusts on the part of the drill collar instead ofupward thrusts. The same dashpot effect is present in both Figs. 8 and9.

It is apparent that a drill collar assembly such as the drill collarassembly 24 of Fig. l may comprise a variety of individual drill collars25, the variety including any of the individual drillcollars shown inFigs. 2, 4, 6, 7, 8 and 9 or similar individual drill collars. Forexample, a drill collar assembly 24 may include the individual drillcollars 2511, 25o and 25d of Figs. 4, 6 and 7 respectively. Thus in someof the individual drill collars such as the individual drill collarshown in Fig. 4, the relatively movable material will respond primarilyto downward thrusts of the drill column; in other individual drillcollars such as the individual drill collar shown in Fig. 6 therelatively movable material will respond primarily to upward thrusts ofthe drill column; and in still other individual drill collars such asthe` individual drill collar shown in Fig. 7 the relatively movablematerial in Seel/.ing a normal intermediate position will have arelatively mild and yielding action with respect to low amplitudemovements of the drill column but will fully oppose movements ofrelatively large magnitude. The individual driil collars of Figs. 8 and9 may be added to such a drill collar assembly or may be substituted forindividual drill collars of Figs. 6 and 4 respectively. As heretoforepointed out, the individual drill collars of Figs. 8 and 9 operate withless violent impact of the solid material against the ends of `theannular chambers and in addition are characterized by a modified dashpotaction.

My description in specic detail of selected practices of the inventionwill suggest various changes, substitutions and other departures from mydisclosure that properly lie within the spirit and scope of the appendedclaims.

I claim:

l. A drill collar for connection between upper and lower portions of adrill column, said upper and lower portions extending upwardly to arotary table and downwardly to a drill bit, respectively, said drillcollar both providing weight for downward pressure on the drill bit andfor minimizing the transmission of vibration and shock forces from thedrill bit to the drill column, said drill collar comprising: inner tubemeans having a longitudinal tlow passage for communication with thedrill column, upper coupling means ixed to the upper end of said innertube means and adapted for connection with the lower end of said upperportion of said drill column, lower coupling mean-s fixed to the lowerend of said inner tube means and adapted for connection with the upperend of the lower portion of said drill column, outer tubular meanshaving an upper end also connected to said upper coupling means andhaving a lower end connected to said lower coupling means, said outertubular means surrounding at least a portion of said inner tube meansand being spaced a predetermined distance therefrom to form a chambertherewith, a passageway extending from the exterior into the interior ofsaid chamber, said chamber containing a selected medium comprising atleast a liquid, said liquid `only partially lling said chamber, means toprovide a liquid-tight seal for said chamber including means to sealsaid passageway, whereby vibratory and shock forces transmitted to saidcoupling means will be at least in part transmitted to said medium, theturbulence of said liquid created by the liow thereof in said chamberthereby dissipating at least some of the energy of said vibratory andshock forces.

2. The invention as defined in claim 1, wherein said selected mediumcomprises both a liquid and solid material, the specific gravity of saidsolid material being difterent from that of said liquid material,whereby vibratory and shock forces transmitted to said coupling meanswill be at least in part transmitted to said solid material and to saidliquid material for movement of one relative to the other andindependently of said coupling means, the turbulence of said liquidmaterial created by the flow thereof past said solid material therebydissipating at least some of the energy of said vibratory and shockforces.

3. The invention as defined in claim 2, wherein said solid material is asingle solid body having a shape to permit its movement vertically insaid chamber.

4. The invention as defined in claim 2, wherein said chamber is anannular chamber, and wherein said solid material is a hollow tube to titin said chamber but being spaced at least from one of the means definingsaid chamber and being vertically movable therein.

5. The invention as defined in claim 4, wherein said solid material hasa specific gravity less than that of said liquid material.

6. The invention as defined in claim 4, wherein said solid material hasa specific gravity greater than that of said liquid material.

7. The invention as defined in claim 2, wherein said solid materialincludes a plurality of particles, the maximum dimension of each ofwhich is small in comparison to the size of the dimensions of saidchamber.

8. The invention as defined in claim 7, wherein said solid material hasa specific gravity less than that of said liquid material.

9. The invention as defined in claim 7, wherein said solid material hasa specific gravity greater than that of said liquid material.

References Cited in the file of this patent UNITED STATES PATENTS331,450 Rothe Dec. 1, 1885 1,314,005 Louden Aug. 26, 1919 1,785,559Ponti Dec. 16, 1930 2,025,100 Gill et al Dec. 24, 1935 2,126,075 WrightAug. 9, 1938 2,712,435 Allen Iuly 5, 1955

